Pacific earthquake: Are scientists underestimating 'superquakes'? (+video)
But the events of 1960, 2004 and 2011 showed that these faults were capable of producing some of the most destructive earthquakes in recorded history, suggesting earthquake researchers need to re-think aspects of how they evaluate a fault's earthquake potential.
"It's time to come up with something new," Goldfinger told OurAmazingPlanet.
Faults are like batteries
When two tectonic plates collide, they build up strain where a fault sticks, or locks, together. Earthquakes release this strain, which is a form of energy.
For decades, scientists assumed faults acted like rubber bands, steadily building up strain and then releasing it all at once, Goldfinger said. The longer the time since the last earthquake, the larger the next earthquake would be, the model predicted.
The problem was researchers failed to recognize that faults can store energy like a battery, Goldfinger said. And just like batteries, they can discharge energy in small amounts, or all at once, he explained.
Goldfinger and other researchers now think if a "small" quake hits, it may not release all of the accumulated energy in a fault. (On a subduction zone, a small quake can still register in the magnitude-8.0 range, which is devastating to nearby cities.)
Thus, a fault can "borrow" stored energy from previous strain-building cycles, generating larger earthquakes than expected, such as those that hit Sumatra and Tohoku, Goldfinger and his colleagues propose in a study published in the January/February 2013 issue of the journal Seismological Research Letters.
"Those models were already being called into question when Sumatra drove one stake through their heart, and Tohoku drove the second one," said Goldfinger, the lead author of the study.